The present invention relates to generally to radio communications. More particularly, and not by way of limitation, the present invention is directed to a base station and method for Orthogonal Frequency Division Multiplexing (OFDM) signal processing by forming OFDM signals from baseband signals and vice versa.
A list of abbreviations utilized herein is provided at the end of the specification.
The current state of the art radio in mobile communication is the WCDMA radio unit. Each WCDMA carrier is about 5 MHz wide, and the state of the art radios can send up to 4 such carriers within a 20 MHz bandwidth. The basic principles are illustrated by the base station in FIG. 1. Four input signal sample streams are forwarded to respective spreaders 10 and the spread signals are forwarded to respective radio units 12. The output signals are combined in adders 14 to form the 20 MHz output signal to be transmitted from the base station.
LTE, which is not based on WCDMA but on OFDM/OFDMA, will require transmission in bandwidths up to 20 MHz. The basic principles are illustrated by the base station in FIG. 2. A single input sample stream is for-warded to a serial/parallel converter 20, the output of which is processed by an IDFT block 22, typically implemented as an IFFT block. A cyclic prefix adder 24 adds a cyclic prefix to the output signal from IDFT block 22, and the resulting signal is forwarded to a radio unit 12 for transmission.